chore: changelog 1.0.8 — doc polish

CHANGELOG.md

@@ -2,6 +2,16 @@
 
 <!-- markdownlint-disable MD024 -->
 
+## [1.0.8] - 2026-08-06
+
+### Changed
+
+- **API.md**: Added full HTTP status code matrix (table with 12 codes) and rate limit headers documentation.
+- **DEPLOYMENT.md**: Added troubleshooting table (8 common symptoms with check/fix).
+- **MONITORING.md**: Full rewrite with architecture diagram, 7 scrape targets, 8 alert rules, key metrics, troubleshooting.
+- **SECURITY.md**: Full rewrite with threat model diagram, TLS/HSTS config, network isolation, secrets management, incident response.
+- **Architecture docs**: Filled Level 2 building blocks (Mermaid diagram, 5 subsystems with code locations) and Level 3 module breakdowns (chat: 9 modules, playout: 6 modules, frontend: 10 modules).
+
 ## [1.0.7] - 2026-08-06
 
 ### Added